Respiratory Syncytial Virus (RSV)

Respiratory syncytial virus, or RSV, is a virus that attacks the
mucous membranes of people's respiratory tracts (the nose, throat, windpipe,
and the bronchi and bronchioles (the air passages of the
lungs). (The term syncytial means that the virus causes cells -- in
this case, cells of the mucous membranes -- to merge together into larger
cells which, however, don't work as well as the original non-infected cells.)
The virus only infects humans.

In older children and adults, RSV usually causes very bad colds with lots
of clear nasal drainage, but it can also cause laryngitis and bronchitis, and
can trigger or worsen attacks if you happen to have asthma or other chronic lung
problems. Since you do not stay completely immune to RSV for life once
you have had it, you can get it again and transmit it to other people as well.
It usually takes 2 to 8 days after you are exposed to RSV before you become
sick. Once you have RSV you will likely shed RSV particles for 3 to 8 days,
but small infants who have been infected may be contagious for up to 4 weeks.

In small infants RSV also causes mucus membrane damage and clear drainage.
However, because babies and their air passages are small, an RSV infection
can clog up the air passages much more easily. RSV
bronchiolitis
(inflammation of the small air passages) and RSV pneumonia are very common
during the season (usually in the winter and early spring -- I myself
admitted six babies to the hospital with RSV in two days over Thanksgiving
weekend, 1997). Babies with RSV cough a lot -- sometimes the cough
sounds just like that of
whooping cough -- and can have trouble getting enough oxygen if the
infection is bad enough. Babies born prematurely, especially those with
lasting breathing problems, are especially likely to have severe problems
with RSV.

There are several ways to test for RSV. We can grow the virus in cultured
cells, or we can look for antibodies to the virus in a patient's blood
(although we have to take two or more sample days or weeks apart and show
that the RSV antibodies have increased). We can also use antigen-antibody
tests to look for the virus: these tests give results in hours, but are not
as accurate as the culture and blood antibody tests.

We do not yet have a vaccine that protects against RSV. However, we
have immune globulins that will give temporary immunity to patients,
and that we give to children (such as babies born prematurely) who are most
likely to have life-threatening RSV infections. The best prevention involves
good handwashing, and keeping small babies away from anyone known to have
RSV (and possibly even from anyone with a bad cold).

Since RSV is a virus, the antibacterial
antibiotics will not help at
all, although they might be needed for a child who gets a bacterial infection
on top of an RSV infection. Unlike most viruses, there is a medicine,
ribavirin, which can block RSV infections. There are many problems with
ribavirin: it must be inhaled, so a patient on ribavirin must be in a mist or
oxygen tent or on a ventilator, and it is known to cause birth defects in
animals (it has not been proven that people are at risk, but if you are
pregnant you should be nowhere near a hospital room where ribavirin is being
given). These days, hardly anyone resorts to ribavirin for treatment of RSV.

We also now have available
immune globulin specifically for RSV. These come in two forms: an immune
globulin produced from patients who have had RSV and are now immune to it, and
another that is produced by recombinant DNA technology. The recombinant immune
globulin can be given by your child's doctor in the office; the other form must
be given through an IV, and is usually given only in the hospital. These
immune globulins can be given to patients who are particularly at risk for RSV,
such as premature babies. Unfortunately the RSV immune globulin needs to be
given every month during the RSV season. In severe cases we may
give RSV immune globulin to a baby with active RSV if she is due for a
dose anyway, since that can help her get rid of the virus faster. Your
doctor can give you more details, and help you determine whether this is
a good idea for your child.

PLEASE NOTE: As with all of this Web site, I try to give
general answers to common questions my patients and their parents ask me
in my (real) office. If you have specific questions about your
child you must ask your child's regular doctor. No doctor can give
completely accurate advice about a particular child without knowing and
examining that child. I will be happy to try and answer
general questions
about children's health, but unless your child is a regular patient of
mine I cannot give you specific advice.